Replaceable blade propeller assembly

ABSTRACT

The disclosure teaches a novel means for detachably mounting blades on a propeller hub. The blades can be assembled on the hub, and blade replacements can be made, following simple instructions and without special training. The novel structure has various advantages which are also disclosed.

O United States Patent 1 [111 3,764,228 Shook Oct. 9, 1973 [54] REPLACEABLE BLADE PROPELLER 787,745 4/1905 Freid 416/214 ASSEMBLY 1,010,929 12/1911 Loetzer 416/214 1,122,925 12/1914 Henrichsen 416/214 Inventor: Frederick 28th 3,563,670 2/1971 Knuth 416/169 x Street Phoemx 85016 FOREIGN PATENTS OR APPLICATIONS [22] Flled 1971 699,649 12/1930 France 416/207 21 Appl. No.: 186,052

7 Primary Examiner-Everette A. Powell, Jr.

Att Ch 1 E. C t 521 US. (:1 416/93, 416/134, 416/212, may ares a es 416/214 51 Int. Cl B63h 1/20 [57] ABSTRACT [58] Field of Search 416/134, 214, 93 M, The disclosure teaches a novel means for detachably 416/212 mounting blades on a propeller hub. The blades can be assembled on the hub, and blade replacements can 5 References Ci d be made, following simple instructions and without UNITED STATES PATENTS special training. The novel structure has various ad- 1 16 414 6/1871 Cochrane 416/244 X vantages which are also disclosed. 123,274 l/I872 McCay 416/214 4 Claims, 5 Drawing Figures 1oz I #4100 1a Q -18a 9. vi

1 4 Q 48 N 101. 36a.

REPLACEABLE BLADE PROPELLER ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to propeller assemblies for use with marine engines, and the invention is particularly directed to the art of manufacturing propeller assemblies with replaceable blades.

The propeller assemblies generally in use on boats at the present time do not have replaceable blades. Although replaceable blades are known, they are not widely used because the prior art replaceable blades are not as rugged as the non-replaceable prior art blades, and the replaceable blade tends to break where it joins the hub. Moreover many prior art replaceable blades are difficult for laymen to install.

The one-piece propeller assemblies are characterized by another set of problems. The non-detachable blade assemblies frequently suffer damages to the blades of the propellers from hitting objects in water such as floating logs, stumps, rocks, etc. If a blade of a propeller is bent or broken, the propeller assembly must be taken to a professional for repairs. These repairs are costly and time consuming and inconvenient to obtain, and two or three weeks down time for repairs is not at all unusual. A blade is quite often good for only one repair because in the process of repairing a broken blade the metal is crystallized at the point of repair. Ifa blade is broken or bent a second or possibly third time, and cannot be repaired, the entire assembly must be replaced.

Furthermore, the possibility of damaging the propeller beyond use in an out-of-the-way place requires the carrying of a spare in the boat. The one-piece hub and propeller assembly is bulky and requires a large amount of storage space, and storage space in a boat is usually at a premium.

Blades of differing pitches are best suited to various boating requirements. For example, a l7-pitch blade may be best for doing repair boat work, such as pulling skiers. For general purposes an l8-pitch is convenient and for high speed cruising a 19-pitch is preferred and more economical. The availability of space in most boats prohibits carrying multiple one-piece propeller assemblies for the various purposes.

Another disadvantage which occurs in one-piece assemblies arises from the method by which they are constructed. The one-piece assembly is likely to have unbalanced blades. When the mold maker forms his pattern, he forms the mold section for each blade independently of the other blade sections. The sections of the mold should be the same for each blade, but minor differences in the molds appear, causing a variance in the shape and weight of the blades on a single propeller. Other potential for imbalance is present when the propeller material is injected into the propeller mold. The pressure on the blade cavities of the mold varies and 'tends to fill the mold forming the blade on one side of the hub more densely and fully than it fills the blade mold on the other side of the hub. Further differentiation between blades may occur in the process of cleaning up the flash on the cast propeller. Therefore, it quite often results that the blades on a one-piece propeller assembly are not equally balanced.

The present invention overcomes the prior art disadvantages by providing matched sets of replaceable blades. The blades are matched because each blade, whether found in sets of two, three or four, is made in the same mold, and the manufacturing characteristics of each blade are therefore the same. Thus, the balance of the propeller assembly in this invention approaches the ideal without any modifications of the blades after the parts leave the factory. The space requirements of the blades of this invention are minimal because they can be nested together. Only one hub is required even if blades of varying pitch are stored in the boat for replacement and use for alternative purposes.

It is calculated that replaceable blades according to the invention herein can be installed by the owneroperator at one-third the cost of the repair of a single blade on a one-piece assembly, and that as few as two repairs to a one-piece assembly would pay for the whole cost of a hub and set of blades constructed in accordance with this invention.

Down time is virtually eliminated with this invention because the replaceable blades can be carried in the boat at very little expense in terms of space, and the replacement can be made by anyone with the aid of a very simple tool. Replacements can be made on the spot in remote areas which are inaccessible other than by water. Because each blade is formed in the same mold the balance is nearly perfect without further adjustment, and a balanced prop is assured without resort to sophisticated balancing procedures.

Another advantage of the present invention is that a versatile range of uses is possible with replaceable blades of varying pitch. Because of the minimal space requirements for storing the replaceable blades of this invention, multiple purpose sets can be included on any trip without sacrificing a significant amount of boat storage space needed for other purposes. Furthermore blades made of special purposes materials may also be purchased, used only when needed, and thereafter conveniently removed from the hub and stored until a subsequent need arises.

These and other advantages will become apparent to those skilled in the art from consideration of the following detailed description of the invention and a study of the drawings in which:

FIG. 1 is a perspective view of the propeller assembly with one of the propeller blades detached.

FIG. 2 is a cross section of the device of FIG. 1 along the lines 2 2.

FIG. 3 is a plan view of an end of the hub.

FIG. 4 is a partial plan view of an alternative embodiment of the invention.

FIG. 5 is a cross section of the device of FIG. 4 along the line 5 5.

SUMMARY OF THE INVENTION This invention provides a propeller assembly designed to be used in a marine environment. The principal use envisioned is for boat engines where the device of this invention is attached to a standard propeller shaft. In its simplest aspect, the device of this invention has a hollow cylindrical hub which has a flange at one end, conveniently formed integrally with the end of the hub. A groove or mortise is formed in the flange surface facing the second or other end of the hub. Another flange, which is a separate piece, is also mortised and fashioned with means for affixing it to the other end of the hub. Each of the blades, which can be 2, 3 or 4 to a propeller set, has an ear set to a desired pitch and integrally formed with an arcuate base which is shaped to closely fit the outer surface of the hub. The base of each blade is tenoned at longitudinally opposite ends to dove-tail in the mortised flanges when the detachable flange engages the second end of the hub. A means for preventing the rotational movement of the blades around the hub is also provided so that when the hub is turned the surfaces of the blades will bear against and displace water according to the pitch of the blades. A means for attaching the propeller assembly to the propeller shaft is also required, but it is not necessarily a part of this invention. In a preferred embodiment of this invention the detachable flange is constructed in two parts. The first part which slips freely over the second end of the hub, is a compression ring carrying an O-ring which bears against the tenored portion of the base of the blade to provide resilient containment of the blade. The mortise is urged against the tenon by means of the second part a retainer nut threaded to engage the second end of the hub and which contacts the compression ring opposite the tenon.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first illustrative embodiment of this invention is depicted in FIGS. 1, 2, and 3. The majorcomponents of the basic invention are the hub 10, the detachable blade 12, the compression ring 44, and the retainer nut 16. The detachable blade 12 has a base 18 which has a concave surface 20. The latter has the same radius of curvature as, and closely fits, the convex surface 22 of the hub 10. In this embodiment three blades 12 are used to make the set. The base 18 of each blade forms an arc subtending an angle of 120 such that when all three blades are in place the sides 24 touch, and the blades 12 form an outer cylinder around the hub 10. The base 18 is provided at the longitudinal ends 26 of the base 18 with tenons 30, 32 which are shaped to dovetail respectively into a mortise 34 on a fixed flange 36 which is integrally formed at one end 38 of the hub and a mortise 40 formed by the outwardly flaring surface 42 of the compression ring 44 and the convex surface of the hub 10. A slot 46 is provided in the outwardly flaring surface 42 of the compression ring 44 to receive an O-ring 48 which serves to provide a resilient cushion for the tenon 32, thus providing a snug fit for the base which can be used to adjust minute casting variations but nevertheless providing for some resiliency. The compression ring 44 is held in place by a retainer nut 16 which is provided with left-hand threads on its inner surface 54 which correspond to and engage left-hand threads on the convex surface of the hub 10.

Rotation of the blade .12 around the hub 10 is prevented by means of slots 60 in the convex surface 22 of the hub 10 which engage corresponding keys 62 protruding from the concave surface 20 of the base 18 of the blade 12. The retainer nut 16 has a series of six scallops 64 equidistantly spaced around the inside perimeter of the retainer nut 16, which, in conjunction with one of the complementary semi-circular counter bores 66 at the other end 68 of the hub 10, provide a receptacle 70 for an anti-rotation lug 72. The counter bores 66 and the anti-rotation lug 72 are suitably threaded for engagement. The counter bores 66 are 150 apart. The scallops 64 are 60 apart. This arrangement makes it possible to position the compression ring 44 on the hub 10 within a tolerance of a few thousands of an inch relative the ends 26 of the base 18. The O-ring 48 also provides the resilient pressure needed to make the minute adjustment in spacing required in causing a counter bore 66 and a scallop 64 to register. Furthermore, without the provision for the anti-rotation lug the high torque generated by the turning of the propeller would gall the threads of the retainer nut and the hub. The high torque prevents the loss of the anti-rotation lug 72.

The core is a standard item for use in attaching V propeller hubs to power shafts. It is held in place by friction. Between the inner wall 82 of the hub 10 and the outer wall 84 of the core 80 is a vibration damper 86 which is made out of a ring of suitable elastomer.

The retainer nut 16 has drilled holes 14 to accommodate a common pin spanner wrench (not shown). In the drawing, the head 86 of the lug 72 is broached for an Allen wrench (not shown), which could be a part of the pin spanner to provide a wholly convenient onepiece tool for use with the invention.

In an alternative embodiment (FIGS. 4 and S) the hub 10a is constructed with longitudinal shoulders 90 which extend radially from the hub 10a. Necks 92 having a narrower width than the shoulders 90 form a radial extension of the shoulders 90. The base 18a of the blade 12a has a notch 94 in the concave surface at each side 96 traversing the length of the side 96. When the blades 12a are assembled on the hub 100 the notches 94 in the sides 96 of the base 18a form a groove which closely fits the projecting necks 92. The retainer nut (which also serves as a compression ring) has apertures 100 which register with the conduits 102 formed by the bases 18a in cooperation with the hub 10a and its shoulders 90. Thus conduits 102 are provided for the passage of exhaust gases through the propeller assembly when used in conjunction with suitable exhaust apparatus. The retainer nut 98 is provided with left-hand threads 1l0 which engage left-hand threads 112 on the hub 10a. A mortise 40a is integrally formed in the retainer nut 98. In the alternative embodiment the O-ring 48a is seated in a groove 106 in the fixed flange 36a.

Although only two embodiments of the invention have been described in detail it will be apparent to those skilled in the art that many modifications and substitutions can be made with respect thereto which are within the scope of the appended claims.

I claim:

1. A replaceable blade propeller assembly for use with marine engines which comprises a hollow elongate hub, an outer cylinder comprising a plurality of interchangeable arcuate blade-bearing bases, means for preventing rotational movement of said bases relative said hub, means for preventing longitudinal movement of said bases relative said hub comprising mortised flanges disposed on said hub longitudinally spaced to receive the ends of said bases, tenons on said bases adapted to engage said flanges, at least one of said flanges comprising a freely moveable compression ring, a retainer nut, means for adjusting said retainer nut to position said compression ring to define close tolerances between said tenons and mortises and to prevent galling of the threads of said nut and hub comprising threaded engagement between said hub and said nut, a plurality of spaced scallops formed in the inside perimeter of said retainer nut, at least one semi-circular counter bore complementary to said scallops formed in the end of said hub, said scallops and counter bore adapted to register successively upon incremental turns of said retainer nut, and an anti-rotation lug adapted to threadedly engage said counter bore and to lock said nut by occupying a scallop registered with said counter bore.

2. The device of claim 1 with an addition of a resiliently deformable O-ring and means for retaining said O-ring in operative relationship between a said flange and a said base,

3. A replaceable blade propeller assembly for use with marine engines which comprises a hollow elongate hub, an outer cylinder comprising a plurality of interchangeable arcuate blade-bearing bases, means for preventing rotational movement of said bases relative said hub comprising radially extending shoulders longitudinally disposed along said hub, said arcuate bases of said blades having means defining channels in the concave surface of said base along the longitudinal edges thereof, said channels cooperating to receive, closely fit and be supported by said radially extending shoulders, thereby defining a plurality of conduits in cooperation with said shoulders in said hub, means for preventing longitudinal movement of said bases relative to said hub comprising mortised flanges disposed on said hub longitudinally spaced to receive the ends of said bases, tenons on said bases adapted to engage said flanges, at least one of said flanges comprising a longitudinally adjustable retainer nut, adapted to threadably engage an end of said hub, and means for retaining said flanges in threaded engagement with said hub.

4. The device of claim 3 with the addition of a resiliently deformable O-ring and means for retaining said O-ring in operative relationship between a said flange and a said base. 

1. A replaceable blade propeller assembly for use with marine engines which comprises a hollow elongate hub, an outer cylinder comprising a plurality of interchangeable arcuate blade-bearing bases, means for preventing rotational movement of said bases relative said hub, means for preventing longitudinal movement of said bases relative said hub comprising mortised flanges disposed on said hub longitudinally spaced to receive the ends of said bases, tenons on said bases adapted to engage said flanges, at least one of said flanges comprising a freely moveable compression ring, a retainer nut, means for adjusting said retainer nut to position said compression ring to define close tolerances between said tenons and mortises and to prevent galling of the threads of said nut and hub comprising threaded engagement between said hub and said nut, a plurality of spaced scallops formed in the inside perimeter of said retainer nut, at least one semi-circular counter bore complementary to said scallops formed in the end of said hub, said scallops and counter bore adapted to register successively upon incremental turns of said retainer nut, and an anti-rotation lug adapted to threadedly engage said counter bore and to lock said nut by occupying a scallop registered with said counter bore.
 2. The device of claim 1 with an addition of a resiliently deformable O-ring and means for retaining said O-ring in operative relationship between a said flange and a said base.
 3. A replaceable blade propeller assembly for use with marine engines which comprises a hollow elongate hub, an outer cylinder comprising a plurality of interchangeable arcuate blade-bearing bases, means for preventing rotational movement of said bases relative said hub comprising radially extending shoulders longitudinally disposed along said hub, said arcuate bases of said blades having means defining channels in the concave surface of said base along the longitudinal edges thereof, said channels cooperating to receive, closely fit and be supported by said radially extending shoulders, thereby defining a plurality of conduits in cooperation with said shoulders in said hub, means for preventing longitudinal movement of said bases relative to said hub comprising mortised flanges disposed on said hub longitudinally spaced to receive the ends of said bases, tenons on said bases adapted to engage said flanges, At least one of said flanges comprising a longitudinally adjustable retainer nut, adapted to threadably engage an end of said hub, and means for retaining said flanges in threaded engagement with said hub.
 4. The device of claim 3 with the addition of a resiliently deformable O-ring and means for retaining said O-ring in operative relationship between a said flange and a said base. 